Electric plug-in receptacle having a plurality of outlets for attachment plugs



Aug. 28, 1956 R 1, SPENCER ETAL 2,761,113

LECTRIC PLUG-IN RECEPTACLE HAVING A PLURALITY OF OUTLETS FOR ATTACHMENTSPLUGS Filed March 22, 1955 INVEN TORS: Eaberi' Z Jfiencer @harlas EJnczi United States Patent ELECTRIC PLUG-1N RECEPTACLE HAVING APLURAZIJITY OF OUTLETS FOR ATTACH- PLUGS Robert 1. Spencer and :CharlesH. Jandt, Los Angeles, Calif.

Application March 22, 1955, Serial No. $95,952

3 Claims. ((31. 339-159) This invention relates generally to electricalconnectiondevices and is concerned more particularly with a .tnultipleelectric plug-in receptacle by which a plurality of the .electric cordsof appliances, lamps, etc., may be :Connected :to a.-source ofelectricity.

Electric service outlets installed in walls are usually .provided with apair of doublepronged electric sockets into which "the prongs or contactfingers of appliance cord plugs are insertable to connect the appliancesor lamps to the source of electricity. Due to the large number of lampsand appliances commonly found in the home and the fact that several ofthese electrical products may be used simultaneously, it frequentlyoccurs that the two electricsoekets may be insufiicient to meet theneed. For this reason, it is the practice to employ a multiple socketattachment .or auxiliary receptacle which has a pair of mainprongsreceivable in the contact openings or sockets p of the wallreceptacle, the contact fingers or prongs of the multiple outlets of thereceptacle attachment thus receiving electric current from the electricwiring. The .prongs of the appliance cord plugs, being frictionally heldin the contact openings .of the auxiliary receptacle, serve to conveythe electric-current to the. appliances.

Auxiliary multiple socket plug-in receptacles used for the purposeoutlined above are widely used and take many forms. In general, suchdevices consistof molded plastic blocks -or hollow casings having a pairof main prongs at one side by which the auxiliary plugwin receptacle iselectrically connected to the contacts of the wall receptacle. The pairsof contact openings, into which the appliance cord plugs are insertable,are invariably located at the :outer face .of theblock or casingor inslopingfaces .of the same, the plugged-in appliance cords thusprojecting .from the plug-in receptacle .in a direction normal, ornearly normal, to the wallet theroom. Such plugging in of the.appliance.cords results ;in an unsightlytcondition .whichimpairs theappearance .oftheroom, theipoints .of connection -of the plugs beingspaced "at a tconsiderable {distance from the wall due to the relativelylarge block like .nature .of the .plug-in receptacle and the applianceicords depending from the receptacle .in loops. As is well .known, theoutwardly projecting and looping appliance icords create .a hazardous.cendition, .Lproviding obstacles .ovenwhichapersonmayitrip and fall.ilmaddition, since the appliance cords .project :at right-angles fromthe plug- ;in receptacle, that is, parallel to the main iprongs, the act,of ,pulling a 'cord from .the receptacle .frequently results :ininadvertent displacement of the .entire assembly of receptacle and cards.from :the service-outlet .and .in some cases where the room is lighted,by lamps :connected to .the receptacle, the light may be extinguished.This results in confusion and inconvenience since re-plugging of thereceptacle block into the service outlet in the dark is not easilyaccomplished.

It is an object of ourjinvention to obviate the disadvantages anddeficiencies of conventional plug-in receptacles referred to above byproviding a multiple soc'ket'plug-in receptacle "in which the contactprong openings extend .in planes :at right-angles to plane .of the mainplug-in prongs. By this provision, the appliance cords plugged .into theauxiliary receptacle project therefrom in a plane ,parallel to 'the wallof the room and the occurrence of unsightly and dangerous loopsprojecting outwardly into the room is effectively avoided. In addition,since the plugged .in appliance cords are removable from the receptacleby pulling them =.in.a plane normal to the main prongs, it follows thatany tendency to accidentally dislodge the receptacle from the serviceoutlet in the wall is eliminated. Preferably, the seriesof prongedoutlets of the auxiliary receptacle are arranged at the bottom face ofthe receptacle sothatthe-appliance cords extend downwardly toward thefloor, this feature making it possible to arrange the cords along thebaseboard without the occurrence of loops or bendszintheicords.

Another object .of1the'inventioniis to provide a plug-in receptacle, ofthe character referred to, :which takes the form of a flat, rectangularplate of minimum thickness and of a length which is substantially equalto the width of the cover plate .of a service outlet so that when thereceptacle is plugged .into the service outlet it appears to be anintegral .part thereof. Preferably, the plate-like, plug-in receptacleis .of .a :height such that it covers only one=of the outletsof the.double socket service receptacle so that the other outlet remainsaccessible for use.

Another object of .the invention is to provide a plug-in receptaclewhich comprises .a pair of relatively thin, rec tangular plates moldedfrom thermo-setting plastic material and :each having a horizontal,longitudinally extend ing, cored groove ,provided .with verticalbranches extending .downwardly therefrom, to the bottom edge of theplate, the mating vertical portions together forming openings or-socketsfor receiving the prongs of appliance cord end plugs. Disposed in rthefork-shaped grooves of the plates are similarly shaped .bus bar havingdepending legs, vthe lower .ends of which provide contact fingers, .onewithin each prong socket, for engagement with the prongs of the .endplugs iinserted therein. Ac cording .to the invention, the bus barshaveintegral strips which project at right-angles thereto and outwardlythrough the back plate to serveas .the mainprongs of the plug-inreceptacle. The ,two plates are joined together in .face-to-iface:relation by any suitable means, such as dowels-or screws,.or bycementing.

A .further :object of .the invention is to provide a plug- .inreceptacle, .of theclass referred to, which issimple in construction andadapted for .economical mass production and one which is highlypractical and safeto use.

IFurtherpbjects rof our invention will appear from the followingdescription (and from the drawing which is intended for the purpose ofillustration only, and in which:

Fig. liis a part+sectional, front elevational view of our improvedplug-in electrical receptacle;

Fig. 2 isaplanzyiew of the same;

Figs. 3 and 4 are across-sectional views, taken respectively on lines.3-3 and '44 of Fig. l; and

i Fig. 5 is atrontfface view-of one of the plates forming one-halfof'the :receptacle casing.

Referring to the drawingain detail, :the plug-in electrical receptacleincludes a rectangular casing 10 which, as shown, -.comprisesarelatively thin, rectangular back plate 11 .and aisimilardrom plate 12.The :plates 11 and 12 are molded from :thermosetting plastic materialand preferablykhave a width substantially equal to the width of .aconventional service outlet cover plate such as indi cated at 13. Theheigh'bof 'the plates 11 and 12 is substan'tially equal *to one half theheight of the cover plate 13. The plates 1-1 and 12 are assembled inface-to-face relation and their combined thickness is preferably equalto one-half inch, or less.

The back plate ill of the receptacle casing is provided in its frontface with a cored horizontal groove or recess adjacent its upper edgeportion. The plugin receptacle is herein shown, by way of example, as ofthe triple outlet type and in such a receptacle the back plate 11 isprovided with six branch grooves 16 which project downwardly from thehorizontal groove 15 in equally spaced relation. The lower ends of thebranch grooves 16 provide sockets 17, the lower ends of which arereduced in width to provide narrow openings 13 extending to the loweredge of the plate. The back plate 11 is also provided with a threadedaperture 19 and a pair of rectangular holes 20 and 21.

The front plate 12 of the plugin receptacle casing llll has in itsrearward face'a groove 15, 16', 18 similar to the groove 15, 16, 18 ofthe plate 11, the several grooves mating when the two plates are joinedin abutting face-to-face relation.

The plug-in receptacle includes a brass contact element which has ahorizontal bus strip or bar 26 adapted to fit snugly within thehorizontal groove 15 of the back plate 11. The element 25 also has threelegs 27 which are formed integrally with the bus bar 26 and extenddownwardly therefrom to be positioned within alternate branch grooves16. The lower end portions of the legs 27 are located within alternatesockets l7 and are twisted at 28 and formed to provide curved contactfingers 30. The contact element 25 has a flat strip 33 which projectsrearwardly through the hole 20 to serve as 2. prong.

The front plate 12 is also provided with a contact element 25 of a shapesimilar to that of the element 25, having a horizontal bus bar 26,fitting in its groove 15 and depending legs 27' disposed in its branchgrooves 16, the legs 27' having curved contact fingers 30' locatedwithin alternate sockets 17. The contact element 25 has a rearwardlyextending prong 33'.

The rectangular plastic plates 11 and 12, with their contact elements 25and 25' in place therein, are joined with their respective front andrearward faces in engagement, an insulator strip 35 being interposedtherebetween. With the plates joined together, the prong 33 extendsrearwardly through the hole 21 so that both prongs 33 and 33 projectfrom the back of the plug-in receptacle. The plates 11 and 12 may bejoined in a variety of ways such as by interengaging dowels and sockets,by cementing their engaging faces together, or by a screw 36 passingthrough a hole in the front plate 12 and screwed into the hole 19 of theback plate 11.

With the plates 11 and 12 thus joined, the contact fingers 38 and 30 ofthe respective contact elements 25 and 25' are disposed in alternatesockets 17, as clearly shown in Fig. 1. The contact fingers thus arearranged in three separate pairs 30, 30', each pair providing areceptacle or outlet, all having their openings at the bottom edge ofthe casing 10.

To apply the multiple outlet receptacle to use, it is simply placedagainst the cover plate 13 of a service outlet and'its prongs 33 and 33'are forced into a pair of prong openings 4%} thereof. In this manner,the plugin receptacle is mounted flat against the cover plate 13 byreason of the frictional engagement of its prongs 33,

'33 in the openings 40. The bus elements 25 and 25' thus are connectedto the service outlet in a manner such that electric current passes tothe several contact fingers 3t and 36]. When the plug-in receptacle iselectrically joined to one of the sockets of the service outlet as shownin Fig. l, the other socket remains exposed and may be utilized in theusual manner, the plug-in receptacle covering only one-half of the coverplate 13. Preferably, the plug-in receptacle is so mounted that itssockets 17 are lowermost, as shown in Fig. 1.

To electrically connect a lamp, radio or appliance to the serviceoutlet, it is only necessary to insert the prongs 45 of the end plug 46of the double wire cord 47 into a pair of adjacent sockets 17 of thecasing 10. By this procedure, the prongs 45 frictionally engage thecontact fingers 30, 30' which, as explained above, are connected inparallel with the electrical circuit of the building. Appliance cordsthus connected to the plug-in receptacle are adapted to projectdownwardly therefrom, parallel to the wall, and upon reaching the floorthey may be bent to extend along the baseboard or floor in the requireddirections.

Connection of the appliance cords to the fiat plug-in receptacleprovides a very satisfactory solution to the problems encountered whenconventional plug-in blocks are employed for the purpose. The manner inwhich the cords are plugged into the receptacle results in a greatlyimproved appearance. In addition, the weight of the appliance cords isapplied at a point close to the wall so that any tendency for thereceptacle to pivot downwardly due to the weight of the cords iseffectively minimized. This represents an important improvement overconventional plug-in receptacle blocks wherein the appliance cords areplugged in at outer faces of the block and thus create a cantileverforce tending to pivot the block down- Wardly and disengage the prongsof the block from the contacts of the service outlet. It is alsoimportant to note that disconnection of an end plug 46 from thereceptacle casing 10 is effected by simply pulling the end plugdownwardly and that such applied force, at right-angles to the mainprongs 33, 33', will not pull the receptacle from the service outlet.This is also an important improvement over conventional plug-in blockswhere the cords are removed by pulling them outwardly in a directionparallel to the main prongs, such applied force frequently resulting indisplacement of the plug-in block fro-m the service outlet.

In accordance with the provisions of the patent statutes, we have hereindescribed the principle of the invention, together with the structurewhich We now consider to represent the best embodiment of the invention.We wish to have it understood, however, that various modifications mightbe made in the plug-in receptacle structure without departing from thespirit or scope of the invention, as defined in the appended claims.

We claim as our invention:

1. An electrical plug-in receptacle, comprising: a flat, rectangularcasing of dielectric material having a plurality of plug-in sockets inan edge thereof; and a pair of identical contact elements within thecasing, each element having a plurality of integral, coplanar, contactfingers, the fingers of the elements being located in alternate sockets,said contact elements having integral prongs projecting from a fiat faceof said casing, normal to the plane of said longitudinal edge, saidcontact fingers in each pair of sockets having curved extremitiesextending in planes normal to the fingers and frictionally engageablewith the prongs of an appliance cord end plug inserted into saidsockets, normal to the plane of said edge.

2. An electrical plug-in receptacle, comprising: a flat, rectangularcasing of dielectric material having a plurality of plug-in sockets in alongitudinal edge thereof; and a pair of identical contact elementsWithin the casing, each element having a plurality of coplanar contactfingers, the fingers of the elements having right-angularly twistedextremities located in alternate sockets, said contact elements havingintegral prongs projecting from a flat face of said casing, normal tothe plane of said longitudinal edge, said contact fingers in each pairof sockets being frictionally engageable with the prongs of an appliancecord end plug inserted into said sockets, normal to the plane of saidedge.

3. A plug-in receptacle as defined in claim 2 in which the casing has agroove provided with a first portion extending parallel to saidlongitudinal edge and a plurality of branch portions extending normal tosaid edge and providing said sockets, and in which each contact elementhas a bus bar portion disposed in a said first portion of a said groove,and a plurality of coplanar legs projecting normal to said bus barportion and disposed References Cited in the file of this patent inalternate branch portions, said legs having right-ang1 1- UNITED STATESPATENTS lat-1y extendlng, curved, flexble contact fingers at them 2 44367 A H 1 4 free ends disposed within alternate sockets, each pair of gM et "g adjacent sockets and the contact fingers therein consti- 5 z 5322? Z 2 t l J I utmg a receptacle for a doub epronged electrlc plug2,637793 Korecki H y 5 1953 2,702,893 Paulson Feb. 22, 1955

